桩基后压浆对深基坑降水渗流场的影响

发布时间：2018-10-30 14:14

【摘要】：钻孔灌注桩后压浆后,与坑外含水层相比,基坑范围内含水层的渗透系数减小,这对基坑降水渗流场具有比较明显的影响。某广场式建筑由五幢塔楼和地下车库组成,采用桩侧后压浆钻孔灌注桩,基坑开挖深度21m,承压含水层组厚10m,透水性较强,采用敞开式完整井降水,井位主要沿基坑周边布置。在对水文地质条件进行概化后,建立了地下水三维非稳定流数值模型,进行了非均质渗流场模拟,并与均质渗流场作比较。结果表明,坑内后压浆区域的渗透系数减小后,坑内水力坡度变陡,单井涌水量减小,井数应相应增加;若模型计算域全部按注浆后的渗透系数考虑,则会严重降低补给强度、低估基坑总涌水量;在相同的降深要求下,坑内后压浆后渗透系数减小、但坑外渗透系数不变,基坑总补给量基本没有变化。现场监测与模拟结果较为一致。研究成果对类似工程地下水控制有一定的借鉴意义。
[Abstract]:Compared with the aquifer outside the pit, the permeability coefficient of the aquifer in the area of foundation pit decreases after the grouting of the bored pile, which has obvious influence on the seepage field of the foundation pit. A square building is composed of five towers and underground garages. The pile side grouting bored pile is used. The excavation depth of foundation pit is 21m, the confined aquifer group is 10m thick, the permeability is strong, and the open intact well dewatering is adopted. Well location is mainly arranged along the perimeter of foundation pit. After the hydrogeological conditions are generalized, a three-dimensional unsteady flow numerical model of groundwater is established, and the heterogeneous seepage field is simulated and compared with the homogeneous seepage field. The results show that the hydraulic gradient in the pit becomes steeper and the water inflow of a single well decreases and the number of wells increases when the permeability coefficient of the post-grouting area in the pit decreases. If the calculation field of the model is considered according to the permeability coefficient after grouting, the recharge intensity will be seriously reduced and the total discharge of foundation pit will be underestimated. Under the same depth reduction requirement, the permeability coefficient after grouting in the pit decreases, but the permeability coefficient outside the pit remains unchanged, and the total foundation pit supply is basically unchanged. The results of field monitoring and simulation are consistent. The research results can be used for reference for groundwater control in similar projects.
【作者单位】：上海广联环境岩土工程股份有限公司环境岩土技术中心;上海市基坑工程环境安全控制工程技术研究中心;
【基金】：上海市科学技术委员会(12231200702,13231201004,14DZ1207802)资助
【分类号】：TU463

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